Water circulation systems for ponds, lakes, municipal tanks, and other bodies of water

ABSTRACT

A circulation system for bodies of water. In one set of embodiments for larger bodies of water, modified horizontal plate designs are provided at the entrance of the draft hose. The plate designs have sections that pivot downwardly as the flotation platform and depending draft hose are rapidly raised in high wave conditions to let the water escape downwardly out of the hose. Adaptations to the floats for the elongated arms of the platform are also made to essentially eliminate the creation of any damaging torques on them from high waves. Another set of embodiments are particularly adapted for smaller systems in municipal water tanks for thorough mixing of the water and treatment to kill undesirable ammonia oxidizing bacteria and prevent or at least inhibit their return.

RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.11/733,009 filed Apr. 9, 2007, which claims the benefit of U.S.Provisional Patent Application Ser. No. 60/791,091 filed Apr. 10, 2006,which applications are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the field of circulation systems for ponds,lakes, municipal tanks, and other bodies of water. It particularlyrelates to the field of such circulation systems for relatively largeand deep bodies of water in which high waves may periodically develop.It also relates to circulation systems for smaller and shallower bodiesof water such as in municipal or similar water tanks and containers.

2. Discussion of the Background

One group of improvements of the present invention has particularapplication to larger and deeper bodies of water that may develop largewaves (e.g., 4-6 feet high or more). Circulation systems for such bodiesthat float on the surface of the water must then rise vertically theheight of each wave and often must do so very quickly (e.g., within afew seconds or less). Typical circulation systems have a draft hoseattached to a flotation platform floating on the surface. The hoseextends downwardly (e.g., 20-50 feet or more) into the body of water andcan have a diameter on the order of 3 feet. In operation, suchcirculation systems are drawing a large volume of water up the drafthose and as the flotation platform rises with each wave, the attacheddraft hose must also rise with it.

In many such circulation systems, it is desirable to control thedirection and level of the water being drawn into the bottom of thedraft hose by providing a horizontal plate or other structure adjacentthe inlet to the hose. However, a problem can occur that the largevolume of water in the hose cannot quickly escape back out of therestricted bottom or inlet of the hose as it is lifted with a wave.Consequently, great stresses are put on the flotation platform and hoseof the system as the flotation platform rises with each wave andattempts to pull up with it the very heavy hose full of water. Inextreme cases, the stresses can damage or even destroy the flotationplatform as well as the hose and other parts of the system. As indicatedabove, the primary cause of the problem in such systems is that thecolumn of water in the hose cannot escape fast enough out the restrictedbottom of the hose, particularly in high seas with waves cresting at 4-6feet or more every few second or so.

Larger and deeper bodies of water which may develop high and violentwaves can also present problems to the float arrangements for suchcirculation systems. That is, many systems have floats that areessentially rigidly attached to elongated arms extending outwardly ofthe central platform of the system. The floats commonly extenddownwardly from the ends of the arms and serve to suspend or support theplatform via its arms on the surface of the water. Under normalconditions with gentle waves, such float arrangements work fine as thereis enough time for the water to move around the floats without exertingany large side forces on the arms. However, when high winds or otherelements develop, the waves can become quite high and violent. In thesesituations, there can be large forces exerted on the floats from thewater pushing against them. The side forces on the floats then translateinto a twisting force or torque on the elongated arms fixedly attachedto them and the platform. This twisting of the float arms can eventuallyfatigue them to the point of failure. In extreme cases, the side forcesmay even snap or otherwise damage the arms so they do not support theplatform properly atop the water.

Other improvements of the present invention have particular applicationsto municipal drinking and similar tanks of water. Such tanks or othercontainers for potable water have special needs and requirements. Forexample, it is desirable that all of the water in the tank be thoroughlyor uniformly mixed so there are essentially no dead spots, including inany corners and along the walls and floor of the tank. Such mixing ispreferably accomplished relatively quickly by the circulation system andmaintained so over extended periods of operation. It is also desirablethat the circulation system be designed to easily and quickly injectdisinfectants such as chlorine and chloramines into the circulatingwater.

With these and other problems and desired characteristics in mind, theadaptations of the present inventions were developed.

SUMMARY OF THE INVENTION

The present invention involves improvements in various aspects ofcirculation systems for ponds, lakes, municipal tanks, and other bodiesof water.

In one set of improvements, modified horizontal plate designs areprovided at the entrance of the draft hose that depends from theflotation platform into the depths of the body of water. In a firstdesign, the plate member has two sections pivotally mounted to eachother. The two sections are biased by floats to align horizontally witheach other when the body of water is relatively calm. The horizontallyextending plate sections are adjacent the bottom of the hose and serveto direct the incoming water substantially horizontally into the hose.In this manner, the plate with its sections extending horizontallyessentially controls or limits the depth of the water being drawn intothe hose.

In adverse conditions with high waves, the plate sections can desirablyfold or collapse downwardly toward each other and a vertical plane asthe flotation platform and attached hose are lifted up with the wave. Inthis regard, the water escaping out the bottom of the rapidly risinghose will overcome the upward forces of the floats on the plate sectionsand will collapse the sections toward each other. In extreme conditions,the force of the escaping water will fold the plate sections together toextend substantially adjacent one another in a vertical plane. In doingso, the plate sections in the fully open or folded position offer littleif any resistance to the column of water escaping out of the bottom ofthe hose as the hose is being lifted with the wave. Stresses and damageto the flotation platform, hose, and other parts of the circulationsystem are thus minimized in high wave conditions.

In a second design, the plate member has a number of pie-shaped ortriangular-shaped sections pivotally mounted at their bases to asurrounding circular ring. In contrast to the first design, thetriangular-shaped sections fold or collapse downwardly away from eachother rather than toward each other as the flotation platform andattached hose are lifted up with the wave. Otherwise, the first andsecond plate designs operate substantially in the same manner to achieveessentially the same desired result.

Another aspect of the present inventions for bodies of water that maydevelop large and violent waves includes adaptations to the floats forthe elongated arms of the platform. In this regard, the floats aremounted to the ends of the arms so as to be substantially free to moveessentially universally relative to the arms. The floats extend aboverather than below the ends of the arms and are connected by flexiblearrangements such as chains, cables, ropes, and ball joints. Violentwaves or forces in the water can then press sideways against and movethe floats without creating damaging forces or torques on the arms.

Still other improvements of the present invention serve to particularlyadapt the circulation system to municipal and similar tanks orcontainers for drinking or potable water. Such systems have specificneeds and requirements. Among them, the system needs to thoroughly mixthe water in a relatively quick and sustainable manner to reach allareas of the tank. The system also needs to be able to injectdisinfectants in an efficient and relatively quick manner. In thepresent invention, the inlet arrangement to the draft hose has beendesigned to draw water uniformly in essentially all directions (360degrees) across the bottom or floor of the tank into the draft hose.This aids in a thorough mixing of the water as well as disinfecting ofthe water and surfaces of the tank including its walls and floor. Thesystem has particular application in municipal water tanks disinfectingwith chloramines, which can develop films of undesirable ammoniaoxidizing bacteria on the surfaces of the walls and floors. The thoroughcirculation pattern of the present system in this regard produces flowalong and against the tank walls and floor to effectively bring thechlorine in the chloramines into contact with the undesirable surfacebacteria to kill them and prevent or at least inhibit their return.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a circulation system for arelatively large body of water such as a pond or lake in which thesystem creates an overall flow pattern in the body of water out to itsedges and down to its depths.

FIGS. 2-4 schematically illustrate the sequential operation of themodified flap valve plate of FIG. 1 which essentially collapses as theflotation platform and attached draft hose are lifted by a wave.

FIGS. 5-7 further illustrate the operation of the modified flap valveplate in the sequential operation of FIGS. 2-4.

FIG. 8 shows the modified flap valve plate with its two sections pivoteddownwardly to the fully open position.

FIGS. 9 and 10 are views looking upwardly from beneath the modified flapvalve plate showing it in its substantially horizontal position of FIGS.1, 2, and 5.

FIG. 11 illustrates another embodiment of the modified flap valve plateof the present invention with a different arrangement of floats.

FIGS. 12-15 show an additional embodiment of the flap valve plate inwhich the plate has a plurality of triangular-shaped sections pivotallymounted to a circular ring for pivotal movement downwardly and away fromeach other rather than toward each other as in the earlier embodiments.

FIG. 16 is a side view of the float arrangement of FIG. 1 in which thefloat arms extend above the surface of the water and the floats arefixedly attached beneath them.

FIG. 17 is a view taken along line 17-17 of FIG. 16.

FIG. 18 is a view of an adaptation of the circulation system of FIG. 16in which the float arms extend outwardly under the surface of the waterversus the ones of FIG. 16 and the floats are positioned above the armsby flexible members such as chains to avoid creating damaging twistingor torque forces on the arms as can occur with the arrangement of FIGS.16 and 17.

FIGS. 19-21 illustrate another flexible arrangement for attaching thefloats of FIG. 16 to the outer end portions of the float arms to alsoavoid creating damaging twisting or torque forces on the arms.

FIG. 22 is a side view of a circulation system adapted for use inmunicipal or similar tanks of potable water.

FIG. 23 is a top view thereof taken along line 23-23 of FIG. 22.

FIG. 24 is a perspective view of the bottom inlet arrangement to thelower portion of the draft hose.

FIG. 25 is a top view of the bottom inlet arrangement taken along line25-25 of FIG. 22.

FIGS. 26 and 27 illustrate a modification to the inlet arrangement ofFIGS. 22 and 24 wherein the height of the inlet off the floor of thetank can be adjusted if desired.

FIG. 28 shows a modified shape of the housing of the bottom inletarrangement to the draft hose.

FIG. 29 is a view taken along line 29-29 of FIG. 28.

DETAILED DESCRIPTION OF THE INVENTION

As schematically shown in FIG. 1, the water circulation system 1 of thepresent invention for large bodies of water such as a pond or lake 2includes an upper flotation platform or floating portion 3 with a drafthose or tube 5 depending downwardly from the platform 3 toward the lakebottom 4 to the water inlet 7 to the hose 5. The flotation platform 3includes a plurality of floats 9 (e.g., three) supported thereon. Thefloats 9 extend outwardly of the central axis 13 (FIG. 1) of theplatform 3 and are preferably evenly spaced thereabout. The floats 9extend far enough out from the central axis 13 to provide a relativelystable and buoyant support structure for the system 1 including itssolar panels 11, electric motor 15, dish 17, and impeller at 19 as wellas for the depending draft hose 5 and the structure of the water inlet7. One or more cables or lines 21 as in FIGS. 2-4 can also be providedto extend from the flotation platform 3 down to the bottom portion 5′ ofthe hose 5.

In operation as best seen in FIG. 1, water is drawn up through the hose5 to the surface 6 by the impeller at 19 on the flotation platform 3.The draw of the impeller 19 up the hose 5 also induces the additionalflow 8 along the outside of the draft tube 5 aiding to create theoverall flow pattern of the system 1. To limit or control the direction23 (see FIG. 2) of the flow of water into the bottom portion 5′ of thehose 5 and into the surrounding induced flow 8 of FIG. 1, asubstantially horizontally extending plate member 20 is supportedadjacent the inlet opening 7 to the hose 5. The inlet opening 7 as shownin FIG. 2 is actually formed by the gap or opening 25 between the bottomportion 5′ of the hose 5 and the plate member 20 spaced below it. Theplate member 20 extends substantially about and outwardly of thevertical axis V (FIG. 2) The inlet opening 7 in turn preferably extendsalong and about the axis V. The horizontally extending plate member 20of FIG. 2 in this regard substantially prevents the circulation system 1from drawing in water below the level of the plate member 20. The platemember 20 also aids in establishing the overall circulation in the bodyof water 2 of FIG. 1 passing laterally above the plate member 20 intoand up the hose 5, outwardly of the flotation platform 3, downwardlyinto the body of water, and again laterally into the hose 5.

In high wave conditions with the flotation platform 3 being raised 4-6feet or more every few seconds or less, the flotation platform 3 andattached hose 5 can be rapidly and often violently lifted from theposition of FIG. 2 to that of FIG. 4. To prevent the horizontal platemember 20 from unduly restricting or limiting the escape of water out ofbottom portion 5′ of the hose 5, the plate member 20 is designed withtwo sections 22 pivotally mounted to each other. Consequently, as theflotation platform 3 and attached hose 5 are raised (see FIGS. 3-4), theplate member 20 essentially folds or collapses with the sections 22being pivoted downwardly toward each other. With the sections 22substantially adjacent one another in the open position of FIG. 4,little if any resistance is offered to the column of water escaping outthe bottom portion 5′ of the hose 5. Stresses are then greatly reducedon the flotation platform 3 and attached hose 5 as well as other partsof the circulation system 1.

FIGS. 5-7 are further views of the operation of the pivoting flap valve20. As shown and as the flotation platform 3 and hose 5 are being raisedby the wave of FIGS. 2-4, the valve plate sections 22 are moved fromtheir normal horizontal position (FIG. 5) downwardly toward each otherabout the common horizontal axis H (FIG. 6) and eventually to theirfully open position of FIG. 7. The fully open position is also shown inFIG. 8. In being moved to the fully open position, the forces of thefloats 24 that bias or raise the plate sections 22 to the horizontalposition of FIGS. 2 and 5 are overcome by the force of the water columnescaping out the bottom portion 5′ of the hose 5. As perhaps best seenin FIGS. 9 and 10 looking upwardly from beneath the plate 20, one ormore chains 26 or other restraining mechanism is preferably provided.The chains 26 serve to limit the upward extent to which the sections 22(FIG. 9) can pivot away from the fully open position and each other. Inthis manner, the sections 22 are prevented from going beyond thehorizontal position of FIGS. 2 and 5. The chains 26 of FIG. 9 areaffixed to each section 22 and extend substantially along horizontalaxes with the sections in the position of FIGS. 9 and 10. The floats 24in this regard can be any buoyant material (e.g., closed-cellpolystyrene) and are preferably placed within protective housings suchas the stainless steel ones 28 of FIGS. 9 and 10. Other floatarrangements such as the ball-shaped floats 24′ in FIG. 11 could also beused if desired. In this arrangement, the upward movement of thesections 22 beyond the horizontal is restrained by the elongated membersor legs 26′. The legs 26′ as shown extend downwardly from the circularring 27 of the draft hose bottom portion 5′ to abut and prevent thesections 22 from moving upwardly beyond the horizontal.

Another embodiment 20′ of the plate member or flap valve is illustratedin FIGS. 12-15. As shown, the plate member 20′ includes a plurality ofpie-shaped or triangular-shaped sections 22′. The base of eachtriangular sections 22′ is mounted (e.g., by hinges 30 on the undersideof the circular ring 32 as in FIG. 15) for pivotal movement about therespective horizontal axes H′. Adjacent sections 22′ then pivot aboutadjacent axes H′ (FIGS. 12 and 15) that intersect one another. Thesections 22′ have floats 24 and can be restrained from moving upwardlybeyond the horizontal position of FIG. 12 or downwardly away from eachother beyond the open position of FIG. 14 by the hinges 30 or bases ofthe sections 22′ abutting the ring 32 or by other restrainingmechanisms. The ring 32 in turn would be supported below the bottom hoseportion 5′ of FIG. 8 by the legs 34 or other structure.

In operation as illustrated, the sections 22′ of the plate member 20′can be pivotally moved about their respective axes H′ from thehorizontal position of FIG. 12 (with the apexes 36 of the triangularsections 22′ adjacent one another) to the open position of FIG. 14. Incontrast to the first embodiment 20 of FIGS. 1-11, the triangular-shapedsections 22′ of the embodiment 20′ of FIGS. 12-15 fold or collapsedownwardly away from each other rather than toward one another as theflotation platform 3 and attached draft hose 5 are lifted up with thewave as in FIGS. 2-4. Otherwise, the first and second plate embodiments20 and 20′ operate substantially in the same manner to achieveessentially the same desired result.

Another problem that can occur with circulation systems 1 on largebodies of water 2 that can develop high and violent waves is fatigue anddamage to the flotation arms. That is, designs such as in FIG. 1commonly have elongated arms such as 31 in FIGS. 16 and 17 that extendoutwardly of the central section 3′ of the flotation platform 3 and itsvertical axis 13. The arms 31 are elongated along axes 33 (FIG. 17) andextend outwardly above the floats 9 (FIG. 16). Each arm 31 has an innerend portion 31′ attached (e.g., by a horizontal pivot) to the centralsection 3′ of the flotation platform 3 with the float 9 then attached toand beneath the outer end portion 31″. In this manner, each arm 31 ispositioned above the float 9 and above the surface 6 of the body ofwater 2.

Under normal conditions with gentle waves, these arrangements work fineas there is enough time for the water to move around the floats 9 and nolarge side forces are exerted on the floats 9. However, when high andviolent waves develop, large and rapid forces F (FIG. 17) in the wavescan push essentially sideways or horizontally against the floats 9.These horizontal forces then translate into twisting or torque forces Ton the float arms 31 about the central section 3′ of the flotationplatform 3 and its vertical axis 13. Eventually, the torque forces Tfatigue the arms 31 to the point the arms 31 may break or otherwisefail, particularly at the attachment to the central section 3′ of theflotation platform 3.

To overcome this problem, the arrangement of FIG. 18 was developed. Init, the elongated arms 31 extend as before outwardly of the centralsection 3′ of the flotation platform 3 but do so with the outer endportions 31″, below rather than above the water surface 6. The floats 9in turn are positioned above rather than below the outer end portions31″ of the arms 31 and are connected by flexible arrangements such asropes, cables, or the illustrated chains 35 of FIG. 18. In this manner,the floats 9 are substantially free to move essentially universallyrelative to the arms 31. Violent waves or forces in the water can thenpress sideways against and move the floats 9 without creating damagingforces or torques on the arms 31. Additionally, the central section 3′of the flotation platform 3 remains more stable in such high waveconditions as the central section 3′ is moved about much less regardlessof the direction the waves push against the floats 9.

As indicated above, the connecting arrangement between the outer endportions 31″ of the arms 31 can be flexible members such as ropes,cables, or the illustrated chains 35 of FIG. 18. The arrangement couldalso be other ones that allow essentially multi-directional freedom ofmovement such as the ball 37 and socket 39 design of FIGS. 19-21.Damaging twisting or torque forces are then not developed on the arms31. Additionally as in the embodiment of FIG. 18, the central section 3′of the flotation platform 3 remains more stable in high wave conditionsas the central section 3′ is moved about much less regardless of thedirection the waves push against the float 9.

FIG. 22 illustrates a circulation system 1 of the present inventionspecifically adapted for use in a municipal or similar tank 41 orcontainer of potable water 2. The tank 41 as shown has a floor 43 and awall arrangement 45 extending upwardly therefrom. The system 1 includesa flotation platform 3, draft hose 5, and impeller 19. The draft hose 5has a tubular main body 47 and a bottom inlet arrangement 51. The mainbody 47 of the draft hose 5 is flexible about its center line andextends from the flotation platform 3 to the bottom inlet arrangement51. The main body 47 of the draft hose 5 as shown in FIG. 22 has anupper portion 47′ that depends substantially vertically downwardly fromthe flotation platform 3. The main body 47 also has a lower portion 47″(see also FIG. 23) that extend substantially radially outwardly of theupper portion 47′ to the bottom inlet arrangement 51 supported andresting on the tank floor 43.

The bottom inlet arrangement 51 as illustrated in FIG. 24 has a chamberdefined by the box-like housing 55. The outlet 57 of the chamber is influid communication with the lower portion 47″ of the main body 47 ofthe draft hose 5. The inlet of slots 59 to the chamber as shown in FIGS.24 and 25 is substantially open about the substantially vertical axis61. In this manner, the impeller 19 of FIG. 22 will then draw water intothe lower portion 47″ of the draft hose 5 via the inlet arrangement 51(FIG. 24) from adjacent and preferably right off of the tank floor 43.This draw across the tank floor 43 will be substantially radially fromall directions (FIG. 25) inwardly toward and substantially 360 degreesabout the vertical axis 61 through the inlet of slots 59 of the chamberof the housing 55 and into the lower hose portion 47″. The inlet slots59 in this regard are defined by the sides 61 and 61′ (FIG. 24) with thelower side 61′ preferably being the tank floor 43. As indicated above,the water is then literally drawn off of the tank floor 43 for athorough and complete mixing of the water 2 in the tank 41. To enhancethis mixing and to aid in maintaining a laminar flow throughout the tank41, the vertical height of the inlet slots 59 is preferably less thansix inches and more preferably on the order of about two to threeinches.

The system 1 of FIG. 22 in a manner analogous to FIG. 1 thus establishesa desirable circulation or flow pattern in the tank water 2. The patternis outwardly of the flotation platform 3 of FIG. 22 along the watersurface 6, downwardly along the surface of the wall arrangement 45,inwardly across the tank floor 43 to the bottom inlet arrangement 51 ofthe draft hose 5, and up the main body 47 of the draft hose 5 back tothe flotation platform 3. This is the case regardless of the shape ofthe tank 41 itself (e.g., cylindrical or rectangular). The circulationin the pattern is preferably slow enough (e.g., 1 ft/sec and preferablyabout 0.5 ft/sec through the hose main body 47) to maintain a laminarflow throughout the cycle. Although the diameter of the hose 5 can vary(e.g., 12 to 36 inches), the flow volume in a 12 inch hose for examplewould be on the order of 350 gallons per minute. This circulationpattern then sets up induced flows such as 8 in FIG. 1 outwardly of thehose 5 which combined with the radially outwardly flow on the watersurface 6 of FIG. 1 and radially inwardly flow adjacent the lake bottom4 serve to thoroughly mix the water 2.

In the embodiment of FIGS. 26 and 27, a substantially horizontal plate20″ is secured (e.g., bolted) below the inlet arrangement 51. The plate20″ is provided with adjustable length legs 60 (e.g., threaded boltspassing through nuts affixed to the plate 20″). With this arrangement,the inlet slots 59 can then be positioned above the tank floor 43 asdesired (e.g., one to twelve inches) and a horizontal incoming flowheight above the floor 43 set by the plate 20″.

The housing 55 defining the chamber of the bottom inlet arrangement 51is shown in FIGS. 22-27 as having flat rectangular or square sides 63and top 63′ but could have other shapes such as the hemispherical origloo shape 55′ of FIGS. 28 and 29. Regardless of the shape, the drawinto the chamber of the housing 55 or 55′ through the inlet slots 59 isstill preferably directed to be from essentially all directions (360degrees) about the axis 61 as in FIGS. 25 and 29. In some applications,it is noted that the tank floor 43 may be inclined somewhat and the axis61 therefor offset from a strictly true vertical. However, in mostanticipated applications, the axis 61 will still be at leastsubstantially vertical.

In both arrangements of FIGS. 22-29 and as perhaps best seen in FIGS. 25and 29, one or more air or vent holes 65 are preferably provided toallow any air or other gases entrapped in the inlet arrangement 51 toescape upwardly into the tank water. The vent hole 65 as illustrated isat a high and preferably the highest point of the inlet arrangement 51.In this manner, the vent hole 65 helps to prevent air or gas pocketsfrom developing that might otherwise create forces tending to tip orlift the inlet arrangement 51 off of the tank floor 43. In botharrangements of FIGS. 22-29 and as perhaps best seen in FIGS. 22 and 28,part of the lower portion 47″ of the main body of the hose 5 preferablyrests on the tank floor 43. As the water level in the tank rises andfalls, the length of the radially extending lower portion 47″corresponding shortens and lengthens. The housing 55 or 55′ in thisregard preferably remains stationary adjacent the lowest point of thetank floor 43 and the flotation platform 3 then drifts horizontally onthe water surface 6 accordingly to maintain the overall configuration ofFIG. 22.

Another adaptation of the system 1 of FIG. 22 to municipal water tanks41 and the treatment of drinking or potable water is the inclusion oflines 71 and 73 for the injection of disinfectant(s) or other materials(e.g., chemicals) into the circulating pattern of the water 2. The lines71 and 73 are in fluid communication with the bottom inlet arrangement51 and the injection in this regard is preferably directly into thechamber of the housing 55 or 55′ of the bottom inlet arrangement 51 asshown. In this manner, the injected disinfectants such as chlorine orchloramines will be quickly and thoroughly mixed in the tank water 2 andmaintained so by the circulation system 1.

As indicated above, the system 1 of FIG. 22 establishes a desirablecirculation or flow pattern in the tank water 2. The pattern isoutwardly of the flotation platform 3 of FIG. 22 along the water surface6, downwardly along and against the surface of the wall arrangement 45,inwardly across the tank floor 43 to the bottom inlet arrangement 51 ofthe draft hose 5, and up the main body 47 of the draft hose 5 back tothe flotation platform 3. The flow pattern as also indicated above ispreferably laminar or at least nearly laminar. The municipal tank water2 of FIG. 22 is then thoroughly mixed to avoid dead spots andundesirably aged water. The disinfectants or other chemicals added tothe water 2 (e.g., through injection lines 71 and 73) are also quicklyand uniformly distributed. This can be particularly important inemergencies when it is necessary to rapidly chlorinate the water 2(often referred to as break-point-chlorination).

The part of the circulation pattern of the present invention actuallyflowing adjacent or against the surfaces of the wall arrangement 45 andtank floor 43 is equally beneficial in controlling bacteria (e.g.,ammonia oxidizing bacteria or nitrifying bacteria) that can cling orattach to the tank walls and floor essentially as a thin film. Suchbacteria obtain energy to survive and grow as well as reproduce byconverting ammonia into nitrites. Nitrites in turn can be very harmfulto humans, even in low concentrations.

The source of the ammonia supporting the bacteria is primarily relatedto the relatively recent use of chloramines (e.g., 4:1 or higher ratioof liquid chlorine and ammonia) versus just chlorine as in the past.Among other things, chloramines have the benefits of being cheaper,safer to handle for the operators, more stable, and longer lasting thanchlorine by itself. The disinfecting process also tends to be slower andcreates fewer undesirable by-products than chlorine used alone.Depending upon many factors including the ratio of the chlorine/ammoniaand the temperature and pH of the tank water, the ammonia in the mixturesafely remains chemically associated with the chlorine and does notbecome free ammonia to serve as food for the bacteria Unfortunately, thedesired ratio (e.g., 4:1) is always being eroded as the chlorine side iscontinually being degraded or consumed performing its primary functionof cleansing the water. If not closely monitored, the ratio can get outof the desired range and ammonia freed to feed the bacteria leading tothe undesirable creation of nitrites. However, such monitoring can bedifficult as a check for chlorine levels tells little about the ammonialevels and checking for ammonia levels could show safe levels but missesthat it is safe because the dangerous bacteria consumed it makingnitrites. Checking for nitrites often indicates a problem but long afterit might have been avoided by simply changing the chloramine ratio ordoing a rapid addition of chlorine. The preferred solution to theproblem as accomplished by the present invention is not to let thebacteria develop in the first place.

That is, the undesirable bacteria not only can cling or attach to thetank walls and floor but also to particles that have settled to thefloor. It is believed that a very high percentage of the bacteria (e.g.,85%) are in the very bottom one inch or so of municipal tanks with theremainder (e.g., 15%) clinging to the tank walls or other structuralmembers (e.g., support pillars) inside the tank. Consequently, in pastsystems, it has been the practice to try to avoid drawing in water fromthe bottom few inches of the tank by setting the hose inlet at leastthat high and often one or two feet above the tank floor. The bottom fewinches or more are then not part of the circulation pattern and thedisinfectant (e.g., chlorine) for the most part does not contact andkill the bacteria. The undesirable bacteria then flourish in themunicipal water tank 41.

This is turn can lead to the need in extreme cases to shut down the tankfor decontamination once the level of nitrites becomes unsafe or torapidly chlorinate the water 2 (break-point-chlorination) as for exampleby adding chlorine through one of the lines 71, 73. Both of whichactions are undesirable and often ineffective solutions. However,because of the circulation or flow pattern of the system 1 of FIG. 22,chlorinated water is passed by and against the surface of the wallarrangement 45 and across the surface of the tank floor 43 to contactand kill the bacteria. Where bacteria already exists in a tank, thepresent system 1 essentially skims across the film of bacteria killingand removing a thin layer at a time until it is all gone leaving a cleansurface. In some applications in this regard, it may be desirable to usethe adjustable height embodiment of FIGS. 26 and 27 in existing tankswith large sediment or bacteria build up on the tank floor to moregradually flush or clean away the build up. The inlet arrangement 51 canthen be progressively lowered until the plate 20″ essentially restsdirectly on the floor 43 itself to maintain the entire tank clean. Withsuch methods, the ammonia oxidizing bacteria can be removed and/orprevented or at least inhibited from growing.

The above disclosure sets forth a number of embodiments of the presentinvention described in detail with respect to the accompanying drawings.Those skilled in this art will appreciate that various changes,modifications, other structural arrangements, and other embodimentscould be practiced under the teachings of the present invention withoutdeparting from the scope of this invention as set forth in the followingclaims.

1. A circulation system for a body of water, said system including aflotation platform, an impeller, and a draft hose with a bottom portion,said draft hose depending downwardly from said flotation platform toposition said bottom portion thereof at a depth below the surface ofsaid body of water, said system further including a plate memberextending substantially horizontally outwardly of a vertical axis andbeing spaced from and below the bottom portion of the draft hose, saidplate member and bottom portion of said draft hose creating an inletopening therebetween to said draft hose, said inlet opening extendingsubstantially about said vertical axis wherein said impeller draws waterfrom the depth of said body of water substantially horizontally throughsaid inlet opening above said plate member up the draft hose toward thesurface of said body of water, said plate member having a plurality ofsections mounted for pivotal movement between a substantially horizontalposition with said sections aligned substantially horizontally and anopen position with said sections respectively pivoted downwardly about asubstantially horizontal axis.
 2. The system of claim 1 wherein eachsection of the plate member has a float attached thereto biasing saidsection toward said horizontal position.
 3. The system of claim 2wherein said sections have a restraining mechanism to limit the pivotalmovement of the sections upwardly away from said open position beyondsaid horizontal position.
 4. The system of claim 1 wherein said sectionshave a restraining mechanism to limit the movement of the sectionsupwardly away from the open position beyond said horizontal position. 5.The system of claim 1 wherein said sections of said plate member aremounted to respectively pivot about a common substantially horizontalaxis downwardly toward and adjacent each other to said open position. 6.The system of claim S wherein said sections have a restraining mechanismto limit the pivotal movement of the sections upwardly away from saidopen position beyond said horizontal position, said restrainingmechanism being affixed to at least two of said sections and extendingsubstantially along a substantially horizontal axis with said sectionsin said horizontal position.
 7. The system of claim 5 wherein saidsections have a restraining mechanism to limit the pivotal movement ofthe sections upwardly away from said open position beyond saidhorizontal position, said restraining mechanism having at least twoelongated members depending downwardly from the bottom portion of saiddraft hose to abut the respective sections of said plate member withsaid sections in said horizontal position.
 8. The system of claim 1wherein said sections of said plate member are mounted to respectivelypivot about substantially horizontal axes wherein adjacent sectionspivot about adjacent, substantially intersecting horizontal axes.
 9. Thesystem of claim 8 wherein each section has a substantially triangularshape with the respective bases of said triangular shapes mounted forpivotal movement about said horizontal axes with said sections pivotingdownwardly away from each other to said open position.
 10. The system ofclaim 9 wherein said triangular shapes have apexes substantiallyadjacent one another with said sections in said horizontal position. 11.A circulation system for a body of water with a surface, said systemincluding a flotation platform, a draft hose depending downwardlytherefrom into said body of water, and an impeller to draw water upthrough said draft toward the surface of the body of water, saidfloatation platform having a central section extending about asubstantially vertical axis and a plurality of elongated arms extendingoutwardly of said central section and the vertical axis thereof, each ofsaid elongated arms having an inner end portion attached to said centralsection of the flotation platform and an outer end portion spacedtherefrom substantially along an axis, each of said outer end portionsbeing positioned below the surface of said body of water and having afloat positioned thereabove on the surface of the body of water andattached to the outer end portion of the elongated arm by a flexiblearrangement to substantially avoid creating torque forces on saidelongated arm about the axis thereof by horizontal movement of the floaton the surface of the body of water caused by wave forces pressingsubstantially horizontally against said float.
 12. The system of claim11 wherein said flexible arrangement attaching the outer arm portion tothe float thereabove is a chain.
 13. The system of claim 11 wherein saidflexible arrangement attaching the outer arm portion to the floatthereabove is a flexible member.
 14. The system of claim 11 wherein saidflexible arrangement attaching the outer arm portion to the floatthereabove includes a ball and socket assembly.
 15. A circulation systemfor a body of water in a tank having a floor and a wall arrangementextending upwardly therefrom to contain the body of water, said systemincluding a flotation platform, an impeller, and a draft hose with amain body and a bottom inlet arrangement supported on the tank floor,said main body of said draft hose being flexible and extending from saidflotation platform to said bottom inlet arrangement, said main bodyhaving an upper portion depending substantially vertically downwardlyfrom the flotation platform and a lower portion extending substantiallyradially outwardly of said upper portion to the bottom inlet arrangementsupported on the tank floor, said bottom inlet arrangement having achamber with an outlet in fluid communication with the lower portion ofthe draft hose and an inlet substantially open about a substantiallyvertical axis, said impeller drawing water adjacent the tank floorsubstantially radially inwardly along said tank floor toward and fromsubstantially 360 degrees about said vertical axis, into the inlet ofsaid chamber, and up through the main body of the draft hose to theflotation platform.
 16. The system of claim 15 wherein the inlet of thechamber is defined by sides with said tank floor substantially definingone side wherein the water is drawn substantially off of the tank floorinto said inlet.
 17. The system of claim 16 wherein the inlet to thechamber defined by said sides extends upwardly from the tank floor forless than about six inches.
 18. The system of claim 17 wherein the inletto the chamber defined by said sides extends upwardly from the tankfloor for about two to three inches.
 19. The system of claim 15 whereinthe inlet to the chamber defined by said sides extends upwardly lessthan about six inches.
 20. The system of claim 19 wherein the inlet tothe chamber defined by said sides extends upwardly for about two tothree inches.
 21. The system of claim 15 wherein said chamber is definedby a housing with substantially flat sides and top.
 22. The system ofclaim 15 wherein said housing has a substantially flat top with at leastone vent hole therein.
 23. The system of claim 15 wherein said chamberis defined by a housing with a substantially hemispherical shape. 24.The system of claim 15 wherein said bottom inlet arrangement has atleast one vent hole therein substantially at a high point of the inletarrangement to allow gas in the inlet arrangement to escape upwardlyinto the water of the tank.
 25. The system of claim 15 wherein acirculation pattern is created in the body of water by the systemoutwardly of the flotation platform along the surface of the body ofwater down the wall arrangement inwardly across the tank floor to thebottom inlet arrangement of the draft hose and up the draft hose back tothe flotation platform.
 26. The system of claim 25 wherein thecirculation pattern created in the body of water is substantiallylaminar flow.
 27. The system of claim 15 further including asubstantially horizontal plate secured below the inlet arrangement andhaving adjustable length legs extending downwardly therefrom.
 28. Thesystem of claim 15 further including at least one line in fluidcommunication with the chamber of said bottom inlet arrangement toinject disinfectant into said chamber and the water being drawntherethrough into the lower portion of the draft hose.
 29. The system ofclaim 28 wherein said disinfectant includes chlorine.
 30. The system ofclaim 28 wherein said disinfectant includes chloramines of chlorine andammonia.
 31. The system of claim 28 including at least a second line influid communication with the chamber of said bottom inlet arrangement toinject a fluid into said chamber and the water being drawn therethroughinto the lower portion of the draft hose.
 32. A circulation method for abody of water in a tank having a floor and a wall arrangement extendingupwardly therefrom to contain the body of water, the method includingthe steps of: (a) providing a flotation platform, an impeller, and aflexible draft hose with a main body and a bottom inlet arrangementsupported on the tank floor, (b) depending an upper portion of the mainbody of said draft hose substantially vertically downwardly from theflotation platform, (c) extending a lower portion of the main body ofsaid draft hose substantially radially outwardly of said upper portionto said inlet arrangement, (d) creating a flow pattern in the body ofwater outwardly of the flotation platform along the surface of the bodyof water, down the wall arrangement, inwardly across the tank floor tothe bottom inlet arrangement of the draft hose, and up the draft hoseback to the flotation platform, and (e) directing the flow pattern todraw water adjacent the tank floor substantially radially inwardly alongthe tank floor toward and from substantially 360 degrees about saidvertical axis into the inlet arrangement and up through the main body ofthe draft hose to the flotation platform.
 33. The method of claim 32wherein said flow pattern is substantially laminar.
 34. (canceled) 35.(canceled)
 36. (canceled)
 37. (canceled)
 38. (canceled)
 39. (canceled)